Sub-properties:

fetchCSS

If true, YUI will attempt to load CSS dependencies and skins. Set this to
false to prevent YUI from loading any CSS, or set it to the string "force"
to force CSS dependencies to be loaded even if their associated JS modules are
already loaded.

lang

This list is matched against the list of available languages in modules that the
YUI instance uses to determine the best possible localization of language
sensitive modules.

Languages are represented using BCP 47 language tags, such as "en-GB" for
English as used in the United Kingdom, or "zh-Hans-CN" for simplified Chinese as
used in China. The list may be provided as a comma-separated string or as an
array.

logLevel

The minimum log level to log messages for. Log levels are defined
incrementally. Messages greater than or equal to the level specified will
be shown. All others will be discarded. The order of log levels in
increasing priority is:

pollInterval

purgethreshold

The number of dynamic <script> nodes to insert by default before automatically
removing them when loading scripts.

This applies only to script nodes because removing the node will not make the
evaluated script unavailable. Dynamic CSS nodes are not auto purged, because
removing a linked style sheet will also remove the style definitions.

Component-specific skin name overrides. Specify
a component name as the key and, as the value, a string or array of strings
for a skin or skins that should be loaded for that component instead of the
defaultSkin.

useNativeJSONParse

Leverage native JSON parse if the browser has a native implementation.
In general, this is a good idea. See the Known Issues section in the
JSON user guide for caveats. The default value is true for browsers with
native JSON support.

Default: true

useNativeJSONStringify

Leverage native JSON stringify if the browser has a native
implementation. In general, this is a good idea. See the Known Issues
section in the JSON user guide for caveats. The default value is true
for browsers with native JSON support.

windowResizeDelay

Delay in milliseconds to wait after a window resize event before firing the
event. If another resize event occurs before this delay has elapsed, the
delay will start over to ensure that resize events are throttled.